The invention concerns a self-propelled implement, specifically an agricultural implement, such as a combine, chopper or tractor or similar, that is equipped with pretensioned, endless track belts, made of a flexible material, which are provided on their inside with guide elements, and controlled via drive wheels and idler pulleys, located on the axles, in that the guide elements engage into clearances of the drive wheels and idler pulleys.
With the here mentioned self-propelled implements, the axles for the drive wheels and idler pulleys are located parallel and in a spaced relation to each other. Normally, the track belt drive is part of the drive train, since a self-propelled implement is further equipped with a steerable axle, onto which bogie wheels are arranged. The steerable axle in agricultural implements is located in the rear. The track belt drives of the suitable self-propelled implements are known in different designs. In general, the rear axle of the track belt drive is propelled. Each drive wheel and each idler pulley consist, in most cases, of two halves, so as to provide the center clearance for the guide elements of the track belt. The guide elements can be designed either by inside grousers or guide bars arranged in line. In order that the side flanks of the guide elements do not contact the facing surfaces of the drive wheels or idler pulleys, respectively, the width of the respective clearance is greater than the width of the guide element. It becomes unavoidable during cornering, that the track belts shift on the drive wheels and idler pulleys. This shifting occurs also during operation of the self-propelled implement on a slope. The side flanks of the guide elements make then contact with the facing surfaces of drive wheels and idler pulleys, so that the wear on the guide bars is relatively high.
The purpose of the invention has the fundamental task to further develop a self-propelled implement of the above described kind in a simple manner, in that the wear on guide elements of the track belts, caused by the unavoidable shifting of the track belts during cornering, and/or on a slope, is significantly reduced, and the life of the track belts is accordingly increased.
The invention solves this problem by providing the drive wheels and idler pulleys, on both sides of the guide elements of the track belts with free pivoting as well as synchronously rotating contact bodies, whose rotating axes are perpendicular and at equal distances to the axles of the track drive.
The shifting of the track belt perpendicular to the moving direction causes now the respective side flanks of the guide elements to impact the contact bodies, which thus are rotated. The direction of rotation is also perpendicular to the moving direction of the track belt. The rotation of the contact bodies eliminates the previously unavoidable friction, which caused high wear. Friction between the drive wheels and/or idler pulleys, made of metal, must be prevented, since the track belts do not resist it, as they are made of rubber or a rubber-like synthetic material.
A constructive, simple solution is achieved, in so far as the contact bodies are designed as rollers with a cylindrical or preferably spherical casing surface. A relatively large surface is covered when the guide elements engage with the rollers, thus, the resulting increased surface pressure remains within acceptable limits. The spherical casing surface results already in a rotation of the respective roller, when the side flanks of the guide elements only slightly run against it. The distances between the contact bodies and/or the rollers, must be kept to a minimum, especially when the guide elements of the track belts are designed as guide bars arranged in line. It should then be avoided that the rollers are crowded into the clearance spaces. It is therefore provided with such a design, that the clearance space between two consecutive contact bodies or rollers, respectively, is less than the depth of a guide bar extending along the moving direction of the track belts. Each guide bar could then support itself on a contact body, or the areas, which are present forward and rearward in the moving direction would support themselves on two consecutive contact bodies. The contact bodies and rollers, respectively, can be pivoted in a constructively simple manner, in that they have front end bosses, which engage in bores of bearing blocks, which, in turn, are preferably bolted to a mounting disc, located at the wheel or idler pulley body. The contact bodies together with the bearing blocks form a collar, synchronously rotating with the wheel or the idler pulley. Since the bearing blocks, for example, detachable through bolts, are connected with the mounting disc, the assembly and, if necessary, the disassembly of the contact bodies is easily performed. A simple construction of the wheels and idler pulleys, nevertheless highly stable under load, is achieved, in that the mounting disc which carries the bearing blocks, is fastened to a thrust ring, concentric to the wheel axle or idler pulley axle, and that the thrust ring is rigidly connected with a wheel hub mounted by means of a flange disc mounted on the wheel axle or idler pulley axle. The mounting disc is then located rectangular and welded to the thrust ring. The mounting disc and the flange disc are connect especially advantageous with the thrust ring. The flange disc is in an especially effective manner connected with the wheel hub and is detachable from the same. The clearances required for the guide elements are designed in the simplest manner, in that each drive wheel and each idler pulley consists of two wheel halves or two pulleys halves, respectively, between which the guide elements of the track belts proceed. In order to decrease slippage between the track belts and the retainer rings it is proposed, that each thrust ring has a friction coating on the side facing the track belt. The friction coating consists of a material with a high friction coefficient.